Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!att!tut.cis.ohio-state.edu!ucbvax!agate!darkstar!ucscb.UCSC.EDU!funkstr
From: funkstr@ucscb.UCSC.EDU (Larry Hastings)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: MIRROR.FIL
Keywords: help, PC-Tools
Message-ID: <10503@darkstar.ucsc.edu>
Date: 1 Jan 91 14:01:29 GMT
References: <13939@chaph.usc.edu>
Sender: usenet@darkstar.ucsc.edu
Organization: Knowledge Dynamics Corporation
Lines: 46


+-In article <13939@chaph.usc.edu>, dchun@aludra.usc.edu (Dale Chun) wrote:
|
| Does anyone know what the file MIRROR.FIL and MIRROR.BAK does with
| PC-Tools? As in, what *exactly* (in as much detail as possible) does
| this file contain and do?
| 
| Can this file be safely deleted without any harm to the system? 
| [... We] are having some bizzare problems with this MIRROR.FIL and
| MIRROR.BAK files on our hard disk.
|
+----------

Those are the FAT backup files written out by "mirror".  "mirror" is a
combination FAT-restoring and deleted-file-tracking utility.  (The "FAT"s are
your disk's File Allocation Tables -- in a nutshell, the lists of what files
are stored where.)

What mirror does is make a direct copy of your hard disk's FAT tables into a
file.  Then, if your FATs get trashed somehow (like a rogue disk-writing
process or a nasty virus) you can restore them.  Mirror can also (optionally)
keep track every time you delete a file, and make it possible to restore
them.  (This is done by loading a small TSR.) By keeping this information, PC
Tool's Undelete can do a much better job of restoring the files than without
it.  (I would guess that Mirror stores deleted file information in the same
file -- I never use it.)

The file that Mirror writes into is called MIRROR.FIL.  If there's already a
file called MIRROR.FIL, Mirror makes a copy of it (calling the copy MIRROR.BAK) 
before overwriting it.  This is useful if you got part of your FAT trashed,
and rebooted, and Mirror ran again -- you can use the old .BAK FAT from before
your FAT got trashed.

When you install PC Tools, as I recall, they automatically insert a call to
Mirror into your AUTOEXEC.BAT, both backing up your FATs and turing on
"deleted-file" tracking.  The manual mentions that if you're having problems
with collisions between Mirror's TSR and other TSRs that you can stop doing
the "deleted-file" tracking but still run mirror to back up your FATs -- this
is what I'd recommend.  If you still have trouble, just remove Mirror from
your AUTOEXEC.BAT -- but I don't think you will.
--
larry hastings, the galactic funkster, funkstr@ucscb.ucsc.edu

I don't speak for Knowledge Dynamics or UC Santa Cruz, nor do they speak for me

"People, it's Fonzie with Teret's syndrome!"--Dennis Miller on Andrew Dice Clay